John Terry claimed the winning goal for Chelsea in the 76th minute, although the ball went in off Nicolas Anelka, as the Blues kept their 100% home record under Ancelotti.

In a stormy second half, Darren Fletcher waved an imaginary card at Atkinson in an apparent attempt to get Chelsea defender Ricardo Carvalho dismissed for a tackle on Wayne Rooney.

Carvalho had already been booked by Atkinson but Fletcher's attempt fell on deaf ears.

It was just one of a number of confrontations between the referee and players from both sides in a tetchy affair which did little for the reputation of English football.

"The Manchester players protested a lot," said Ancelotti. "I don't know why. I don't like this. At the end of a very difficult match, all the players worked very hard - and sometimes it can happen."

Ferguson may now find himself in more trouble with the Football Association after criticising Atkinson's decision-making in the build-up to Terry's winner.

Ferguson, who branded Alan Wiley "unfit" last month, was adamant that Atkinson's judgement was the kind which lead managers and players to "lose faith in refereeing".

Atkinson awarded a free-kick for Fletcher's challenge on Ashley Cole, and Wes Brown appeared to be impeded as Frank Lampard's delivery was turned into the net by a combination of Terry and Anelka.

"Clearly, Darren Fletcher's won the ball - Ashley Cole's never touched and has jumped up in the air - and then (Didier) Drogba's pulled Brown to the ground for the goal," said Ferguson.

"The referee's position to make the decision was absolutely ridiculous - he can't see anything. He's got a Chelsea player (Joe Cole) standing right in front of him - and he doesn't even move.

"It was a bad decision, but there's nothing we can do about it. You lose faith in refereeing sometimes, that's the way the players are talking in there - it was a bad one.

"That goal should never have been allowed. We've dominated the game. We've had great chances to win the match, and that's our fault.

"We had great opportunities to get to the edge of the box and some really good chances in and around the box, but we should be finishing it off.

"We've only ourselves to blame in that respect. But you do need a break - and we never got the break we needed."

Ancelotti admitted Drogba might have been offside for Chelsea's winner but said: "It was very difficult for the linesman to see. There was a lot of concentration of players in the box.

"We are in a good position in the Premier League and in the Champions League. The players have done very well. We have to continue, because there will be other strong matches like that."

Ferguson, meanwhile, admitted the defeat - United's third on the road this season - was more significant than their recent 2-0 reverse at Liverpool.

"The fact is Chelsea go five points clear of us," he said.

"The defeat to Liverpool didn't affect our position in the league."

Chelsea captain Terry and team-mate Anelka were left arguing over who got the winning goal.

Terry said: "I got a touch on it but I think maybe Nico (Anelka) got the second touch - but I'm still claiming it.

"I was watching the stats before the game and I've never scored against them home and away. But Nico's been brilliant today, so he deserves it."

Anelka added: "I think I touched the ball, but maybe John will claim it. We played good football and we had some chances - but we stayed compact in defence."